The Batcave Puzzle is a puzzle found in Ada Wong's campaign in Resident Evil: Desolation. It is a nightmare-induced puzzle created through the T-Incubo Nightmare Toxin and can be found in the Catacombs.
find the 4 Horsemen of the Apocalypse emblem keys scattered throughout the large tomb while evading (and, if necessary, destroying) the many Mannequills surrounding Ada-and Incubo arising from various fountains-along the way.
After gunning past a set of mummy tombs, and various Incubo emerging from them, Ada escapes into a dark narrows, eventually coming across swarms of vampire bats flying in the air. With only a lantern to guide her, Ada slowly proceeds into a continuous loop down the nocturnal, bat-infested straits. After several quick-cutting zombie girl apparitions-each preceded with sounds of Alex's echoing laughter-illuminating off the nearby cavern rocks and apparitions of Jill and Claire pleading "SAVE US!" before being pulled by the chains around their neck into a bladed machine and raised many feet upwards after being decapitated, Ada is then treated to a distant flickering sound as a life-sized hologram of Alex holding a lit candle in front of her petrifying face follows her in front of every surrounding rock in another horrific loop.
Following the eventual burning out of the candle in her fingertips-and the subsequent disappearance of Alex-Ada then finds herself surrounded in large masses of stone coveting a large tomb. The frenziness soon continues as Ada hears Alex's cryptic voice speaking to her through the cavern walls.
"Why, Ada? Why prolong the inevitable? Don't you see? I'm the one gatekeeper to your darkest fears! You, like the rest of the world, will soon cower at my fingertips!"As Alex is talking, the rocks begin to spring to life as Mannequills begin to emerge from the many skull pillars scattered around the large tomb. Ada finds herself in another predicament as she finds the nearby exit sealed off by a 4-piece emblem puzzle and danger lurking around every nearby corner.